Speaker
Description
It has become apparent that Silicon, though an excellent choice as a sensing material for current particle detectors, suffers greatly when exposed to heavy radiation, degrading properties like charge collection efficiency and increasing noise levels. Future collider experiments will require it to withstand stronger radiation fields. Therefore, either a frequent replacement of detectors, a leap in the radiation hardness of Silicon, or a shift to different materials is needed. Wide-bandgap materials are a natural choice, due to their significantly reduced leakage currents, even after irradiation. In recent years, substantial progress in the production of high-quality monocrystalline Silicon Carbide of the 4H polytype has led to a renewed interest in this material.
In this talk, a study focusing on crystal defects in n-type epitaxial 4H Silicon Carbide diodes will be presented. Microscopic defects in the crystal lattice, whether intrinsic or radiation-induced, introduce energy levels in the bandgap, leading to altered electrical characteristics of the material. The study primarily investigates the unirradiated material and its numerous defects. Results from Deep-Level Transient Spectroscopy (DLTS) and Thermally Stimulated Currents (TSC) are presented, complemented by current-voltage and capacitance-voltage measurements. TSC spectra simulations were utilised to correlate DLTS and TSC results, identifying some discrepancies between the spectra obtained with the two techniques. Results from unirradiated diodes are compared with those irradiated using 23$\,$GeV protons at varying fluences up to 1$\cdot$10$^{15}$ protons/cm$^2$.
This study concludes that state-of-the-art 4H Silicon Carbide contains a multitude of defects already present prior to irradiation. These defects are therefore likely intrinsic, such as vacancies, or related to impurities and doping imperfections.
